#!/usr/bin/perl -w

    use strict;


    die "Usage: $0 subset serial\n" unless @ARGV == 2;

    my $subset = shift;
    my $serial = shift;

    open SUBSET, $subset or die "Couldn't open $subset: $!\n";
    open SERIAL, $serial or die "Couldn't open $serial: $!\n";


    my %used;

    $used{$_}++ while <SUBSET>;

    while (<SERIAL>) {print unless $used{$_}}


    __END__